FRIEND: Federated Learning for Joint Optimization of multi-RIS Configuration and Eavesdropper Intelligent Detection in B5G Networks
Organizations: Microwave and Fiber Optics Laboratory, School of Electrical and Computer Engineering, National Technical University of Athens, 9 Heroon Polytechneiou str, Zografou 15780, Athens, Greece · Communications and Intelligent Systems Research Group, University of Hertfordshire, AL10 9AB Hatfield, U.K. · Intelligent Communications and Broadband Networks Laboratory, School of Electrical and Computer Engineering, National Technical University of Athens, 9 Heroon Polytechneiou str, Zografou 15780, Athens, Greece
Abstract
As wireless systems evolve toward Beyond 5G (B5G), the adoption of cell-free (CF) millimeter-wave (mmWave) architectures combined with Reconfigurable Intelligent Surfaces (RIS) is emerging as a key enabler for ultra-reliable, high-capacity, scalable, and secure Industrial Internet of Things (IIoT) communications. However, safeguarding these complex and distributed environments against eavesdropping remains a critical challenge, particularly when conventional security mechanisms struggle to overcome scalability, and latency constraints. In this paper, a novel framework for detecting malicious users in RIS-enhanced cell-free mmWave networks using Federated Learning (FL) is presented. The envisioned setup features multiple access points (APs) operating without traditional cell boundaries, assisted by RIS nodes to dynamically shape the wireless propagation environment. Edge devices collaboratively train a Deep Convolutional Neural Network (DCNN) on locally observed Channel State Information (CSI), eliminating the need for raw data exchange. Moreover, an early-exit mechanism is incorporated in that model to jointly satisfy computational complexity requirements. Performance evaluation indicates that the integration of FL and multi-RIS coordination improves approximately 30% the achieved secrecy rate (SR) compared to baseline non-RIS-assisted methods while maintaining near-optimal detection accuracy levels. This work establishes a distributed, privacy-preserving approach to physical layer eavesdropping detection tailored for next-generation IIoT deployments.
Figures & tables
| ID | Requirement Description | Category | Target (Sub-)System | Challenge | Work |
| R1 | The SoI shall support multiscenario channel data generation reflecting the 5V data paradigm (Volume, Variety, Velocity, Veracity, Value). | Fit (Operational) | MATLAB | SV Data | Current Work |
| R2 | The SoI shall provide reliable preprocessing and feature extraction to ensure balanced and representative datasets. | Fit (Operational) | MATLAB | SV Data | Current Work |
| R3 | The SoI shall incorporate bias–variance control mechanisms (e.g., regularization, cross-validation, early stopping) to guarantee model generalization. | Function (Performance) | PYTHON | Bias–Variance Balance | Current Work |
| R4 | The SoI shall jointly evaluate performance using ML accuracy metrics and communication QoS metrics. | Function (Performance) | MATLAB, PYTHON | Design Priorities | Current Work |
| R5 | The SoI shall integrate data generation and DL/ML decision in real-time to guarantee seamless simulation runs. | Fit (Operational) | MATLAB, PYTHON | MATLAB/PYTHON API | Future Work |
| R6 | The SoI shall integrate data generation and DL/ML in a reproducible manner to maintain interoperability and traceability of experiments. | Non-Functional | MATLAB, PYTHON | MATLAB/PYTHON API | Future Work |
| Parameter | Value/Assumption |
| Frequency | 28 GHz (FR2) |
| Antennas’ Height | APs: 8m, UEs: 1.5m |
| UEs Mobility | 3 km/h |
| Noise | 5 dB |
| Transmit Power | APs: 40 dB, LUs: 23 dB, E: 23 dB |
| Subcarrier Spacing | 120 kHz |